1. Field of the Invention
The present invention relates to an exposure apparatus and a method of exposing a photoresist layer. More particularly, the present invention relates to an exposure apparatus enhancing quality of photoresist patterns when used as an etch mask, and a method of exposing a photoresist layer.
2. Description of the Related Art
Generally, an information processing apparatus requires a display apparatus that transforms an electrical signal processed by the information processing apparatus into an image. Examples of the display apparatus include a liquid crystal display (LCD) apparatus, a light emitting display (LED) apparatus, a plasma display panel (PDP), etc. Such display apparatuses include thin film transistors (TFTs) formed on a substrate. A TFT includes a gate electrode, a channel layer, a source electrode and a drain electrode. The gate, source and drain electrodes are formed by patterning a metal layer. The channel layer is formed by patterning a semiconductor layer such as an amorphous silicon layer. The gate, source and drain electrodes, and the channel layer may be patterned, for example, through a photolithography process.
The photolithography process includes a photoresist film coating process, an exposure process, a developing process and an etching process. The exposure process is performed by an exposure apparatus.
The exposure apparatus is classified as either a scan type or a stepper type. The scan type exposure apparatus includes an optical system, a mask and a substrate plate that supports the substrate. The mask is disposed over the substrate plate, and the optical system is disposed over the mask. Light generated from the optical system is irradiated onto the substrate on the substrate plate through the mask. The substrate on the substrate plate and the mask are transported together, and the optical system may irradiate light onto a local portion of the substrate through the mask. The mask includes patterns and an alignment key for aligning the mask on the substrate.
The scan type exposure apparatus also includes a mask blind disposed over or under the mask. The mask blind prevents light interference between the alignment key and the patterns. The mask blind blocks the patterns when light generated from the optical system is irradiated onto the alignment key. The mask blind also blocks the alignment key when light generated by the optical system is irradiated onto the patterns.
A conventional scan type exposure apparatus reflects light diffusively at an edge portion of the mask blind, which induces exposure defects and generates particles. Thus, it is desired to produce an exposure apparatus that overcomes the above mentioned defects.